The decrease of the eye elasticity according to the rigid sclera theory, that was first stated by Friedman, in the previous decade, has a pathogenenetic role in the development of the age related macular degeneration. According to this theory the decrease of the elasticity of the sclera leads to increase of blood flow resistance inside choroid vessels and in a decrease of the filtration pressure in vessels walls. The sequence of these phenomena leads in defective transfer of fluid and metabolites from the retina to the choroid through the pigment epithelium. These useless metabolism products are accumulated in the Bruch""s membrane, which is theorized to be the beginning of physiological and histological changes, which results in the macular degeneration, and the loss of optical acuity. This pathogenetic model is described in detail in the following publications:
Friedman E. Scleral rigidity, venous obstruction and age-related macular degeneration A working hypothesis. In: Ocular Circulation and Neovascularization. (Doc Ophthalmol Proc Ser) Ben Ezra D, Ryan S J and Murphy (eds). Dordrecht: NijhofVJunk Publishers 1987;50:197-204 35);
Fredman E. A hemodynamic model of the pathogenesis of age-related macular degeneration. Am J Ophthalmol 1977; 124(5):677-82 and
Friedman E, Krupsky S, and Lane A et.al: Ocular blood flow velocity and age-related macular degeneration. Ophthalmol 195 5; 102:640-46
The apparent elasticity of the eyeball for every value of the intraocular pressure can be defined as the inverse gradients of the Intraocular Pressure vs. Eye Volume curve of any given eye. The methodology for the measurement of the apparent elasticity of the eyeball comprises controlled intraocular injection of non-compressible liquid and simultaneous measurement of the intraocular pressure. There are several techniques, which are described in various publications. Indicative references include the following:
Friedenwald J S. Contribution to the theory and practice of tonometry. Am J Ophthalmol 1937;20:985-1024
Van der Werff T J, Phil D. A new single-parameter ocular rigidity function. Am J Ophthalmol 1981;92:391395
In these publications the graphic representations and the mathematical description of the pressure dependence from the injected liquid volume inside the eyeball are presented. One accepted representation of this mathematical expression is the McEwen and St. Helens expression, which can be applied in some other mammal""s eyes as well as to human eyes.
In the face of the hemodynamic model of Friedman and the pathogenic role which this model retains for the increased rigidity of the eye, several surgical techniques have been proposed, which aim to the increase the elasticity of the eyeball by increasing the elasticity of the sclera. For this purpose the sclera is made thinner by application of surface sclerectomies. Thus, the elasticity of the eyeball represents a parameter with clinical interest and it is desirable to be kept stable or be increased as a means for the prevention of the age related macular degeneration, especially in predisposed eyes.
For example, such a predisposition seems to exist in hyperopic eyes, which are also characterized by a relative increase of their thickness, as described in this recent publication:
Chaine G, Hullo A, Sabel J xcexaxcex1l "sgr"uv:.Case-control study of the risk factors for the age related macular degeneration. France-DLMA Study Group. Br.J.Ophthalmol. 1998;82(9):996-1002
This combination of increased thickness along with decreased size makes hyperopic eyes appear less elastic (more rigid) than normal eyes.
There is provided a compressible implant for the increase of ocular elasticity and the prevention of macular degeneration. This implantable intraocular device can be used for the prevention of ocular degeneration and especially of the macular degeneration through increase of total ocular elasticity. The device may be implanted either inside the ocular cavity or in contact with the eyeball. Other applications for the device may also include by way of example the improvement of the hemodynamic status of the eye in any situation associated with insufficient blood inflow. Situations of this kind other than AMD include: diabetic retinopathy, retinal vein thrombosis, retina artery obstruction, and glaucoma.
There is also provided a device implantable either in the eyeball or in the wall of the eyeball, serving for the increase of ocular elasticity where said device is characterized by that it is compressible either as a whole or parts of it. This device may further comprise the required optical elements, which can optically substitute the crystalline lens of the eye. Such a device may further comprise external dimensions and shape similar to the dimensions and shape of the crystalline lens, said device serving for the preservation of the volumetric relationship of the eye in the case that the crystalline lens has been removed. Such a device may yet further comprise a toroid capsule of external diameter about 8 mm to about 16 mm approximately, and internal diameter about 5 mm to about 12 mm, where said capsule is made of elastic or flexible membrane and contains gas or other compressible material. These devices may also comprise a capsule where said capsule is made of elastic or flexible membrane and contains gas or other compressible material and said device additionally features all the necessary optical elements for the optical substitution of the crystalline lens. These devices may also comprise a circular capsule, where said capsule is made of elastic or flexible membrane and contains gas or other compressible material, where said device has or may accept in its center, appropriate optical elements for the substitution of the normal eye lens. These device may also feature a capsule containing gas or other compressible material, said device additionally featuring optical elements where the refractive power of said elements can be controlled through addition or removal of gas or other compressible material from the capsule. In this materialization, appropriate manipulation of the refractive power of the compressible optical element (e.g. by the action of the ciliary muscle) can be used as a means of correction of presbyopia.
There is also provided a device that is capable of being implanted in the eye comprising: a toroid flexible sack, the flexible sack having an elastic side wall, the flexible sack being filled with a compressible material. The compressible material is used to maximize the volume of the flexible sack that can loose its shape to the internal pressure of the eye. The flexible sack contains a quantity of gas or other compressible material to occupy the flexible sack""s maximum volume at the pressure of the interior of the eye. The compressible material in the sack typically includes a pressure of from about 4 mm Hg. to about 40 mm Hg. to maintain the shape of the flexible sack within the eye. When the flexible sack is inflated to its maximum size, the pressure of the compressible material equals the intraocular pressure. The elastic side wall includes a biocompatible material. In these devices the compressible material may be a gas, a foam, a gas contained in a foam. Moreover, the flexible sack may have an external diameter form about 8 mm to about 16 mm. and may further have an internal diameter from about 5 mm to about 12 mm.
There is also provided a device capable of being implanted in the eye comprising: a toroid flexible sack, the flexible sack having an elastic side wall, the flexible sack being filled with a gas, the gas having a pressure of from about 4 mm Hg. to about 40 mm Hg., the gas being selected from the group consisting of air, Nitrogen, Neon, SF6, C3F8 and CO2, the elastic side wall comprising a biocompatible material, the flexible sack having an external diameter from about 8 mm to about 16 mm and an internal diameter from about 5 mm to about 12 mm; and a valve.
There is still further provided a device for implantation into the eye comprising: a flexible sack filled with a compressible material; the flexible sack having an anterior side that is intended to be positioned nearer the anterior surface of the eye and a posterior side that is intended to be positioned nearer the posterior surface of the eye; the flexible sack having an interior surface and an exterior surface; the exterior surface intended to be positioned adjacent the wall of an eye; the interior surface forming a hollow frustum whereby when the device is implanted into the eye the flexible sack will not substantially interfere with light entering the eye; the frustum having an anterior end and a posterior end corresponding to the anterior side and posterior side of the sack; and, the anterior end of the frustum having a smaller diameter than the posterior end of the frustum. In these devices the flexible sack may further have an external diameter greater than about 7 mm. and may still further have the anterior end of the frustum of the flexible sack having an internal diameter greater than about 5 mm.
It is yet further provided a device for implantation into the eye comprising: a hollow frustum shaped flexible sack filled with a compressible material, the compressible material comprising a gas being selected from the group consisting of air, Nitrogen, Neon, SF6, C3F8 and CO2; the sack having a gas pressure from about 4 mm Hg. to about 40 mm Hg.; a valve for adding the gas to the flexible sack; the flexible sack having an elastic side wall; the elastic side wall consisting essentially of a biocompatible material; the flexible sack having an anterior side that is intended to be positioned nearer the anterior surface of the eye and a posterior side that is intended to be positioned nearer the posterior surface of the eye; the elastic side wall of the flexible sack forming an interior surface and an exterior surface; the exterior surface intended to be positioned adjacent the wall of an eye; the interior surface forming a hollow frustum whereby when the device is implanted into the eye and the flexible sack is filled with the gas the flexible sack will not substantially interfere with light entering the eye; the frustum having an anterior end and a posterior end corresponding respectively to the anterior side and posterior side of the sack; and, the anterior end of the frustum having a smaller diameter than the posterior end of the frustum.
There is also provided a device comprising: an optical means for focusing light generally on the retina of an eye; a means for increasing the apparent ocular elasticity of an eye; and, the optical means being contained within the means for increasing the apparent ocular elasticity of the eye, as well as a device comprising: an optical means for focusing light generally on the retina of an eye; and, a means for increasing the apparent ocular elasticity of an eye and for centering the optical means in the eye, as well as a device comprising: an optical means for focusing light generally on the retina of an eye and a means for increasing the apparent ocular elasticity of an eye, and as well as a device comprising: a lens and a means for increasing the apparent ocular elasticity of an eye and for centering the lens in the eye.
There is still further provided a device comprising: an optical means for focusing light generally on the retina of an eye; a means for increasing the blood supply to an eye; and, the optical means being contained within the means for increasing blood supply, as well as a device comprising: an optical means for focusing light generally on the retina of an eye; and, a means for increasing blood supply to the eye and for centering the optical means in the eye, as well as, a device comprising: a lens in an eye and a means for increasing blood supply to the eye, and as well as a device comprising: a lens and a means for increasing blood supply to an eye and for centering the lens in the eye.
There is still further provided an inflatable device for insertion into an eye comprising: a bag means for holding a compressible material, the bag means upon inflation with the compressible material having a donut shape; and, a valve means for permitting the addition of the compressible material to the bag means after the bag means has been inserted into an eye so as to inflate the bag in the eye.
There is still further provided a device capable of being implanted in the eye comprising: a donut shaped elastic bag, the elastic bag having a flexible side wall, the bag being capable of being filled with and holding a compressible material, the bag further being capable of maintaining a pressure once filled with the compressible material of from about 4 mm Hg. to about 40 mm Hg., and, the flexible side wall comprising a biocompatible material.
There is still further provided a device capable of being implanted in the eye comprising: a donut shaped elastic bag, the elastic bag having a flexible side wall and being filled with a compressible material, and, the compressible material exerting a pressure of from about 4 mm Hg. to about 40 mm Hg.
There is still further provided an optically implantable device comprising: a lens; a valve; a semi-flexible sack, the comprising a first elastic side wall, a second side wall, and a third side wall, the first, second and third side walls connected together to form the sack; the second side wall comprising a first relatively ridge optically significant face, and the side wall comprising a second relatively rigid optically significant face; and the lens being contained within the semi-flexible sack and located between the first and second optically significant faces.
There is also provided a method of increasing the apparent ocular elasticity of an eye comprising: inserting an inflatable device in the eye, the device comprising an elastic sack capable of being inflated with a compressible material; and inflating the device with a compressible material to between about 4 mm Hg. to about 40 mm Hg. pressure.
There is also provided a method of increasing the apparent ocular elasticity of an eye comprising: inserting a compressible elastic sack having a pressure of from about 4 mm Hg. to about 40 mm Hg.